Racemization in the Coupling Reaction,Pro-Val+Pro,with the Activated Ester Methods |
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Authors: | Ichiro Tomida Hiroshi Kayahara Ryozo Iriye |
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Institution: | Department of Agricultural Chemistry, College of Agriculture, Shinshu-University, Ina-Shi, Nagano-Ken |
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Abstract: | The degree of racemization in the several activated ester methods of the peptide synthesis was measured in using the critical racemization test, Pro-Val+Pro, with help of gas chromatography. The results were compared with that in the coupling reaction, Leu-Phe+Val, in which no racemization had been reported in the corresponding reaction conditions by F. Weygand et al., when the activated dipeptide esters had been prepared from Z-Leu+Phe-activated esters. The significantly higher racemization was observed in the methods of N-hydroxypiperidine ester and thiophenyl ester, even when the activated dipeptide esters were prepared from Z-Pro+Val-activated esters. On the other hand, almost no racemization was observed in the N-hydroxysuccinimide ester and p-nitrophenyl ester methods. A great extent of the racemization was detected when the activated dipeptide esters were prepared directly from Z-Pro-Val-OH. |
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Keywords: | 5-lipoxygenase liverwort arachidonic acid eicosanoid |
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